1. Field of the Invention
This invention concerns a DC brushless motor apparatus allowing to control the inverter circuit driving by position detection signal obtained through the position detection of a motor apparatus, particularly.
2. Background of the Invention
As for the composition of such DC brushless motor apparatus, for example, compositions as shown in FIG. 9, 21, 30 are disclosed by Japan Patent Application Laid-Open Hei 8-182378. In FIG. 9, 21, 30, the power source section 1, 11, 21 is a DC power source, and obtains an bus voltage Vcc of the inverter circuit 2, 12, 22 for obtaining a pulse modified voltage mentioned below, and obtains a DC power source, for example, by rectification and flattening of the AC power source.
In FIG. 9, the inverter circuit 2, generates multi-phase, for instance, three-phase pulse width modified voltage of U-phase, V-phase and W phase, by controlling transistors TrUxcx9cTrZ, for instance, power transistor, IGBT device or the like, by means of driving signal from the drive circuit 4, creates a rotational magnetic field, and rotates the rotor 3R by supplying respective stator coils 3U, 3V, 3W of the DC brushless motor 3. Though not illustrated, the rotor 3R is composed of a plurality of magnetic poles, for example, by magnetizing two pairs of N pole and S pole, as necessary, an embedded magnet type rotor as mentioned in FIG. 12 below is employed. In this invention, besides magnetic pole formed as rotor and then magnetized, and magnetic pole formed by embedding or fitting a permanent magnet in a rotor, the xe2x80x9cmagnetic polexe2x80x9d includes also those formed by the other methods.
The driving of transistors TrUxcx9cTrZ by the drive circuit 4 is as shown by [Transistor driving waveform] in FIG. 10; fine pulse waveform portions correspond to chopping portions, and the voltage output to the terminal R of U phase, terminal S of V phase and terminal T of W phase appear, for instance, as waveforms before the partial voltage of [Terminal voltage partial voltage waveform] in FIG. 10, FIG. 11.
Here, as U phase, V phase and W phase are alternative current, from the time sequence viewpoint, U phasexe2x86x92V phasexe2x86x92W phasexe2x86x92U phasexe2x86x92V phasexe2x86x92W phase . . . are repeated, for V phase, U phase is the preceding phase, and W phase is the following phase, and for W phase, V phase is the preceding phase, and U phase is the following phase, and further, for U phase, W phase is the preceding phase, and V phase is the following phase.
Consequently, divided by the bleeder circuit of the resistor Rau, Rbu, bleeder circuit of the resistor Rav, Rbv and bleeder circuit of the resistor Raw, Rbw, the waveform of respective voltages input to respective positive terminals, namely respective + terminals of the comparator CPu, comparator CPv and comparator CPw result in U phase partial voltage Ua, V phase partial voltage Va and W phase partial voltage Wa having a waveform like U phase, V phase and W phase of [Terminal voltage partial voltage waveform] in FIG. 10.
The voltage waveform of the imaginary neutral point voltage E0 input to respective negative terminals, namely xe2x88x92 terminals of the resistance comparator CPu, comparator CPv and comparator CPw, by dividing the buss voltage Vcc with the bleeder circuit of the resistor Rd, Rc is as shown by [Power source voltage partial voltage waveform (imaginary neutral point voltage) in FIG. 11. Here, the imaginary neutral point voltage E0 is positioned substantially at the center of the amplitude of U phase partial voltage Ua, V phase partial voltage Va and W phase partial voltage Wa, be setting the resistor Rd, Rc so that [Rb/(Ra+Rb)]=[2Rd/(Rc+Rd)] for respective resistors Raxcx9cRd in respective bleeder circuit of U phase, V phase and W phase.
Then, the comparator CPu becomes U phase position detection comparator, the comparator CPv V phase position detection comparator, and the comparator CPw W phase position detection comparator, and respective transistor TrUxcx9cTrZ of the inverter circuit 2 are driven by delivering the position detection signal Su, Sv and Sw obtained by detecting with respective comparator CPu, CPv and CPw to the control processing portion comprising mainly a microcomputer, namely to the microcomputer 5, by controlling the drive circuit 4 through a predetermined control by the microcomputer 5.
When the rotor 3R rotates, as an induction voltage appears at the stator coil of the phase not conducted with pulse amplitude modified voltage among the stator coils 3U, 3V and 3W, [Rising induction voltage] and [Falling induction voltage] appear after respective spike voltage, as shown in the same drawing.
Then, respective comparator CPu, CPv and CPw detect the intersection with said neutral point voltage in the portion of [Rising induction voltage] and [Falling induction voltage], namely zero cross point P by comparing these voltages, and output this detection signal as position detection signal.
For instance, taking the comparison detection state by the comparator CPu as example, it is as [U phase position detection comparator positive negative input voltage (overwrite)] of FIG. 11, and the zero cross point P is detected, and xe2x80x9cU phase rising position detection pointxe2x80x9d and xe2x80x9cU phase falling position detection pointxe2x80x9d are output as position detection signal, as [U phase position detection comparator output voltage] in FIG. 11. Here, the comparison detection state by the other comparator CPv, CPw is the waveform state, in which the waveform of [U phase position detection comparator positive negative input voltage (overwrite)] of FIG. 9 is shifted by the phase of 120 degrees.
Such DC brushless motor has an advantage of effective use of reluctance torque by performing weak field control, by using an embedded magnet type rotor, namely IPM type rotor as shown in FIG. 12; however, when this IPM rotor is used, a flat portion DX flat in the proximity of the zero cross point P is generated in the induction voltage waveform, making the position detection unstable. as shown in FIG. 13.
Therefore, Jpn. Pat. Appln. Publication Laid-Open No. HEI 11-146685 discloses a composition, wherein, a vertical variation type imaginary neutral point voltage is generated by further adding a plurality of resistors Rf, Rh at the portion where the bus voltage Vcc is divided by respectively equal resistance value resistors Rd, Rc, and alternatively short-circuiting these additional points by respective switching device Tra, Trb according to the control signal from the microcomputer 5, and wherein the zero cross point P is shifted to a position off said flat portion Dx, by comparing and detecting the intersection of this vertical variation type imaginary neutral point voltage and the aforementioned [Rising induction voltage] and [Falling induction voltage] by means of respective comparator CPu, CPv, CPw.
In addition, Jpn. Pat. Appln. Publication Laid-Open No. HEI 11-146685 or the like disclose a composition (called, no chopping composition, hereinafter) wherein the detection is performed by a detection composition similar to said respective position detection, by modifying to the waveform like FIG. 15, without performing the pulse amplitude modification by said chopping.
Such prior art required, disadvantageously, to dispose a switching device, and a composition to control its driving.
On the other hand, in FIG. 21, the inverter circuit 12 rotates the rotor 13R by generating a multi-phase, for instance, three-phased pulse amplitude modified voltage of U phase, V phase and W phase by controlling the transistor TrUxcx9cTrz, for example power transistor, IGBT device or the like, with driving signal from the drive circuit 14, and generating a rotary magnetic field by imparting to respective stator coils 13U, 13V and 13W of the DC brushless motor 13. Though not illustrated, the rotor 13R is provided with a plurality of magnetized magnetic poles, for instance, two pairs of N pole, and S pole.
The driving of transistors TrUxcx9cTrZ by the drive circuit 14 is as shown by [Transistor driving waveform] in FIG. 22; fine pulse waveform portions correspond to chopping portions, and the voltage output to the terminal R of U phase, terminal S of V phase and terminal T of W phase appear, for instance, as waveforms before the partial voltage of [Terminal voltage partial voltage waveform] in FIG. 22, FIG. 23.
Here, as U phase, V phase and W phase are alternative current, from the time sequence viewpoint, U phasexe2x86x92V phasexe2x86x92W phasexe2x86x92U phasexe2x86x92V phasexe2x86x92W phase . . . are repeated, for V phase, U phase is the preceding phase, and W phase is the following phase, and for W phase, V phase is the preceding phase, and U phase is the following phase, and further, for U phase, W phase is the preceding phase, and V phase is the following phase.
Consequently, divided by the bleeder circuit of the resistor Rau, Rbu, bleeder circuit of the resistor Rav, Rbv and bleeder circuit of the resistor Raw, Rbw, the waveform of respective voltages input to respective positive terminals, namely respective+ terminals of the comparator CPu, comparator CPv and comparator CPw result in U phase partial voltage Ua, V phase partial voltage Va and W phase partial voltage Wa having a waveform like U phase, V phase and W phase of [Terminal voltage partial voltage waveform] in FIG. 22.
The voltage waveform of the imaginary neutral point voltage E0 input to respective negative terminals, namely xe2x88x92 terminals of the resistance comparator CPu, comparator CPv and comparator CPw, by dividing the bus voltage Dcc with the bleeder circuit of the resistor Rd, Rc is as shown by [Power source voltage partial voltage waveform (imaginary neutral point voltage) in FIG. 23. Here, the imaginary neutral point voltage E0 is positioned substantially at the center of the amplitude of U phase partial voltage Ua, V phase partial voltage Va and W phase partial voltage Wa, be setting the resistor Rd, Rc so that [Rb/(Ra+Rb)]=[2Rd/(Rc+Rd)] for respective resistors Raxcx9cRd in respective bleeder circuit of U phase, V phase and W phase.
Then, the comparator CPu becomes U phase position detection comparator, the comparator CPv V phase position detection comparator, and the comparator CPw W phase position detection comparator, and respective transistor TrUxcx9cTrZ of the inverter circuit 2 are driven by delivering the position detection signal Su, Sv and Sw obtained by detecting with respective comparator CPu, CPv and CPw to the control processing portion comprising mainly a microcomputer, namely to the microcomputer 15, by controlling the drive circuit 14 through a predetermined control by the microcomputer 15.
When the rotor 13R rotates, as an induction voltage appears at the stator coil of the phase not conducted with pulse amplitude modified voltage among the stator coils 13U, 13V and 13W, [Rising induction voltage] and [Falling induction voltage] appear after respective spike voltage, as shown in the same drawing.
Then, respective comparator CPu, CPv and CPw detect the intersection with said neutral point voltage in the portion of [Rising induction voltage] and [Falling induction voltage], namely zero cross point P by comparing these voltages, and output this detection signal as position detection signal Su, Sv and Sw.
For instance, taking the comparison detection state by the comparator CPu as example, it is as [U phase position detection comparator positive negative input voltage (overwrite)] of FIG. 23, and the zero cross point P is detected, and xe2x80x9cU phase rising position detection pointxe2x80x9d and xe2x80x9cU phase falling position detection pointxe2x80x9d are output as position detection signal, as [U phase position detection comparator output voltage] in FIG. 23. Here, the comparison detection state by the other comparator CPv, CPw is the waveform state, in which the waveform of [U phase position detection comparator positive negative input voltage (overwrite)] of FIG. 23 is shifted by the phase of 120 degrees.
In this detection, the microcomputer 15 takes as position detection signal Su1 the signal obtained by detecting, first, Low to High rising edge or the output of the U phase position detection comparator CPu, when the time has elapsed for the spike voltage in the previous conduction pattern ends, and changes over to the conduction by the conduction pattern from the next transistor TrU to the transistor TrY when the time for the rotor 13R rotates by a certain angle has elapsed.
Then, the microcomputer 15 takes as position detection signal (not illustrated) the signal obtained by detecting, first, High to Low falling edge by the W phase position detection comparator CPw, when the time has elapsed for the spike voltage in the conduction pattern from the previous transistor TrU to the transistor TrY ends, and changes over to the conduction by the conduction pattern from the next transistor Tru to the transistor TrZ when the time for the rotor 13R rotates by a certain angle has elapsed.
Similarly, during the conduction from the transistor TrU to the transistor TrZ, the conduction is changed over from the transistor TrV to the transistor TrZ by the position detection signal (not illustrated) detecting the rising edge of the output of the V phase comparator CPv, and during the conduction from the transistor TrV to the transistor TrZ, the conduction is changed over from the transistor TrV to the transistor TrZ by the position detection signal Su2 detecting the falling edge of the output of the U phase comparator CPv.
During the conduction from the transistor TrV to the transistor TrX, the conduction is changed over from the transistor TrW to the transistor TrX by the position detection signal (not illustrated) detecting the rising edge of the output of the W phase comparator CPW, and during the conduction from the transistor TrW to the transistor TrX, it is operated to change over the conduction from the transistor TrW to the transistor TrY by the position detection signal (not illustrated) detecting the falling edge of the output of the V phase comparator CPv.
Thus, the microcomputer 15 drives the inverter circuit 12 to keep the rotor 13R rotating, by obtaining the position information of the rotor 13R, based on the output waveform of respective comparator CPu, CPv and CPw.
The aforementioned driving state corresponds to an operation state (called stationary operation state, in the present invention) where the rotor 13R can rotate following the increase/decrease of the inverter circuit 12 driving frequency, rotating synchronously with the driving of the inverter circuit 12 by the position detection signal Su, Sv, Sw.
On the contrary, in the starting state where the rotor 13R begins to rotate by starting the driving of the inverter circuit 12, the stationary inertia of the rotor 13R, axial friction, load driven by the rotor 13R or the like make the position detection of the rotor 13R unstable, and it is difficult to operate in synchronization with the position detection signal Su, Sv, Sw.
To solve these problems, Japanese Patent 92682164 or others disclose a composition (called the first prior art, hereinafter) wherein the conduction change over to the rotor coils 13U, 13V or 13W by the position detection signal Su, Sv, Sw of the rotor 13R is not performed immediately after the start of driving of the inverter circuit 12, a forced synchronous operation of the inverter circuit 12 is performed to change over by force the conduction to the rotor coils 13U, 13V or 13W, for example, by means of a clock circuit disposed in the microcomputer 15, and to transit to the synchronous operation by the stationary position detection, after a predetermined operation increasing/decreasing as prescribed by the output voltage of the inverter circuit 12 according to the time.
Besides, without performing said forced synchronous operation, the position of the rotor 13R is detected immediately after the start of the inverter circuit 12; however, taking example of the points of the sections xe2x80x9cTrWxe2x86x92TrYxe2x80x9d, xe2x80x9cTrUuxe2x86x92TrYxe2x80x9d, the detection of the position detection signal Su1 is performed following the time point to execute the changeover operation (called, conversion in the present invention) from previously conducted and operating transistor, for instance, transistor TrW, TrX to the next conductive transistor, for example, transistor TrW, TrY, namely following the conversion time point Wt, as in the [normal operation state] of FIG. 24.
In the detection of the position detection signal Su1, the inverter circuit 12 driving is controlled by setting the time interval (called, position detection masking time) Mt for detecting the position after having restricted not to perform the position detection during a predetermined interval of time, and the delay time (called, conversion delay time in the present invention) Lt for restricting the next conversion time Ut, namely the time point for changing over, for instance, to the conduction of the transistor TrU, and TrT to the time period delayed by a predetermined time from the point of position detection.
In addition to this control, a composition (called, the second prior art, hereinafter) for transiting to the synchronized operation by the stationary position detection, all the way increasing/decreasing the driving frequency of the inverter circuit 12.
Though the [normal operation state] of FIG. 24 does not show but the portion corresponding to the xe2x80x9cU phase rising position detection pointxe2x80x9d, an amplitude variation inverse to the amplitude variation of FIG. 24 appears, similarly as in xe2x80x9cU phase rising position detection pointxe2x80x9d of FIG. 23, also in the portion corresponding to the xe2x80x9cU phase falling position detection pointxe2x80x9d of FIG. 23. Also, V phase and W phase, similarly, position detection portions appear at two positions. There, as mentioned above, if two pairs of N pole and S pole, namely two opposed pairs are magnetized to the rotor 13R, (3 phasexc3x972 points)xc3x97points of number of two opposed poles, in other words, 12 points of detection location portions appear.
In the composition of such DC brushless motor, in relation to the synchronous operation with the rotor 13R as shown in FIG. 25, it is well known a composition wherein the imaginary neutral point voltage E0 is detected by shifting vertically like E01, E02 in FIG. 25, by changing the partial pressure ratio of the bleeder circuit obtaining the imaginary neutral point voltage E0 or the bleeder circuit obtaining respective phase divided voltage, for shifting the detection position of position detection signal Su, Sv, Sw forward or backward the induction voltage, as the intersection Pa or intersection Pb (called, the third prior art, hereinafter), and it goes without saying that, in such a composition, the position detection masking time Mt and the conversion delay time Lt are set to correspond to the intersection Pa or intersection Pb.
As the synchronous operation is forced without position detection, the aforementioned first prior art can not accelerate the time for transiting to the synchronous operation by stationary position detection, and requires a considerably long time, because the inverter circuit 12 output voltage should be increased gradually, with a change in the extent not to provoke the inverter circuit 12 emergency stop, by disordered or irregular driving due to the variation of the load driven by the rotor 13R.
On the other hand, the second prior art has an advantage of being able to transit to the synchronous operation by stationary position detection in a period of time shorter than the first prior; however, when the load driven by the rotor 13R varies, the position detection will be disordered by such variation, and disadvantageously, it can not transit to the synchronous operation by stationary position detection.
Further, in FIG. 30, the inverter circuit 22, generates multi-phase, for instance, three-phase pulse width modified voltage of U-phase, V-phase and W phase, by controlling transistors TrUxcx9cTrZ, for instance, power transistor, IGBT device or the like, by means of driving signal from the drive circuit 24, creates a rotational magnetic field, and rotates the rotor 23R by supplying respective stator coils 3U, 3V, 3W of the DC brushless motor 23. Though not illustrated, the rotor 3R is composed of a plurality of xe2x80x9cmagnetizedxe2x80x9d poles, for example, magnetic poles composed of two pairs of N pole and S pole.
In this invention, the xe2x80x9cmagnetic polexe2x80x9d includes both magnetic pole formed as rotor and then magnetized, and magnetic pole formed by embedding or fitting a permanent magnet in a rotor.
The driving of transistors TrUxcx9cTrZ by the drive circuit 24 is as shown by [Transistor driving waveform] in FIG. 31; fine pulse waveform portions correspond to chopping portions, and the voltage output to the terminal R of U phase, terminal S of V phase and terminal T of W phase are divided by the bleeder circuit of the resistor Rau, Rbu, bleeder circuit of the resistor Rav, Rbv and bleeder circuit of the resistor Raw, Rbw, then the waveform of respective voltages input to respective positive terminals, namely respective+ terminals of the comparator CPu, comparator CPv and comparator CPw result in U phase partial voltage Ua, V phase partial voltage Va and W phase partial voltage Wa having a waveform like U phase, V phase and W phase of [Terminal voltage partial voltage waveform] in FIG. 31.
The voltage waveform of the imaginary neutral point voltage E0 input to respective negative terminals, namely xe2x88x92 terminals of the resistance comparator CPu, comparator CPv and comparator CPw, by dividing the bus voltage Dcc with the bleeder circuit of the resistor Rd, Rc is as shown by [Power source voltage partial voltage waveform (imaginary neutral point voltage) in FIG. 32. Besides, it is sometimes used a composition wherein the imaginary neutral point voltage E0 is shifted upward or downward the imaginary neutral point voltage E0 of FIG. 32, and the position detection signal Su1xcx9cSw2 is obtained by shifting the intersection P forward or backward.
Then, the comparator CPu becomes U phase position detection comparator, the comparator CPv V phase position detection comparator, and the comparator CPw W phase position detection comparator, and respective transistor TrUxcx9ctRz of the inverter circuit 22 are driven by delivering the position detection signal Su, Sv and Sw obtained by detecting with respective comparator CPu, CPv and CPw to the control processing portion comprising mainly a microcomputer, namely to the microcomputer 25, by controlling the drive circuit 24 through a predetermined control by the microcomputer 25.
When the rotor 23R rotates, as an induction voltage appears at the stator coil of the phase not conducted with pulse amplitude modified voltage among the stator coils 23U, 23V and 23W, [Rising induction voltage] and [Falling induction voltage] appear after respective spike voltage, as shown in FIG. 32.
Then, respective comparator CPu, CPv and CPw detect the intersection with said neutral point voltage in the portion of [Rising induction voltage] and [Falling induction voltage], namely zero cross point P by comparing these voltages, and output this detection signal as position detection signal Su, Sv and Sw.
For instance, taking the comparison detection state by the comparator CPu as example, it is as [U phase position detection comparator positive negative input voltage (overwrite)] of FIG. 32, and the zero cross point P is detected, and xe2x80x9cU phase rising position detection pointxe2x80x9d and xe2x80x9cU phase falling position detection pointxe2x80x9d are output as position detection signal, as [U phase position detection comparator output voltage] in FIG. 32. Here, the comparison detection state by the other comparator CPv, CPw is the waveform state, in which the waveform of [U phase position detection comparator positive negative input voltage (overwrite)] of FIG. 33 is shifted by 120 degrees in phase.
In other words, in [R,S,T terminal voltage partial waveform] of FIG. 31, position detection signals are detected cyclically with a time interval corresponding to the rotor 23R speed variation, in respect of one pair of magnetic poles of the rotor 23R, during one revolution of the rotor 23R as Su1xe2x86x92Sw2xe2x86x92Sv1xe2x86x92Su2xe2x86x92Sw1xe2x86x92Sv2 and delivered to the microcomputer 25.
The microcomputer 25 calculates the number of revolution per unit time of the rotor 23R (called number of revolution, in the present invention), for instance, rpm or rps (called collectively xe2x80x9crpmxe2x80x9d, hereinafter) based on the time interval for obtaining respective position detection signals Su1xcx9cSw2, and controls to change the frequency fm of chopping pulse or respective phase voltage (chopping frequency, hereinafter) given from inverter circuit 22 to respective stator coils 23Uxcx9cW or the chopping pulse duty rate du (duty rate, hereinafter) so that this number of revolution rpm be the target number of revolution, for instance, number of revolution rm. Here, the aforementioned number of revolution rpm is the one called, generally, average number of revolution.
When the number of occurrence of position detection signals Su1xcx9cSw2, is twelve per revolution of the rotor 23r, the number of revolution rpm can be obtained by dividing a unit time value, for instance, 1 minute or 1 second by a time value of the time from the time point when the previous one of these twelve position detection signals is obtained to the time point when the next is obtained, measured by an inner clock circuit (not shown) of the microcomputer 25, or the number of revolution rpm in terms of average value can be obtained by dividing a unit time by a time value of the time from the time point when one of position detection signals is obtained to the time point when a plurality of, for instance, ten position detection signals are obtained, and then dividing by the number of signals.
To be specific, as in FIG. 33, if a control with a tolerance of +/xe2x88x92xcex1 is to be executed to the target number of revolution rm1, the control will be executed based on position detection signals Su1xcx9cSw2 by changing the chopping frequency fm or the duty rate fm of respective phase voltage, and when the number of revolution rpm obtained based on position detection signals Su1xcx9cSw2 attains the tolerated upper limit rm1+xcex1, the output voltage Uaxcx9cWa of respective phase (here, Uaxcx9cWa mean output voltage of transistors TrUxcx9cTrZ before said voltage division, and the same applies below) is lowered by changing the chopping frequency fm or the duty rate du.
On the other hand, if tolerated lower limit rm1xe2x88x92xcex1 is attained, it is operated to lowers the respective phase output voltage, and in addition, the operation to vary the output voltage Uaxcx9cWa is performed, by PI control based on the differential value of the detected number of rotation rpm and the target number of rotation rm1 or others. Besides, the control cycle T1 for this control is limited to a relatively small cycle, for instance, 10 msecxcx9c1 sec, and it is controlled to vary often the output voltage Uaxcx9cWa.
In the aforementioned DC brushless motor apparatus, if the load driven by the rotor 23R, namely the driving object of the DC brushless motor apparatus is an air-conditioner, refrigerator or other compressor, it is necessary to adjust the output voltage, by changing often the chopping frequency fm or the duty rate du, as the load varies violently. Such output voltage modification and adjustment increases, disadvantageously, the vibration and noise of the motor itself or compressor.
Further, the present invention concerns an inverter driving electric motor apparatus provided with a function to protect the inverter overcurrent.
Such an inverter driving electric motor apparatus 200 is used, for example, as compression section for coolant compression of refrigeration equipment, air-conditioner or the like, driving source of fan or the like, and various motors such as DC brushless motor is used as electric motor (motor, hereinafter) and, for example, a composition of inverter driving electric motor apparatus 200 wherein a motor 33 is driven by an inverter 32 as shown in FIG. 38 is well-known. In respective drawings below, portions referred to with the same symbol have the same function as portions of the same symbol described in any of drawings.
In FIG. 38, the microcomputer 35 drives the inverter 32 by controlling the drive circuit 34 by delivering a control signal to rotate continuously the motor to the drive circuit 34, and the inverter 32 drives the motor 33 by converting the DC power source 31 into a multiple phase, for instance, three-phased AC power source by means of power transistors (called transistor hereinafter) TU, TV, TW, TX, TZ.
The driving of transistors TUxcx9cTZ is controlled to rotate the rotor 33R synchronously by imparting signals from position detection portions (not shown) for detecting the position of the rotor 33R to the microcomputer 35. The DC power source 31 is, for example, a DC power source obtained by rectifying and flattening the SC voltage obtained by transforming an AC power source (not shown), for instance, commercial AC power source to the required voltage.
The overcurrent detection circuit 36 is a portion for detecting if the DC value detected by a current detection device for detecting current supplying the inverter 32 with current from the DC power source 31, for instance, a current detection resistor Rs disposed on the electric line of the negative side of the inverter 32 exceeds a predetermined value or not, namely overcurrent or not.
Upon the detection of overcurrent, the overcurrent detection circuit 36 delivers an overcurrent detection signal 36A announcing the overcurrent to the microcomputer 35 through an overcurrent anomaly hold circuit 37, the microcomputer 35 controls the operation of the drive circuit to stop driving the inverter 32, and when the driving of the inverter 32 is stopped by this overcurrent protection operation, a control signal from the microcomputer 35 makes the anomaly cancellation circuit 38 cancel the anomaly hold by the overcurrent anomaly hold circuit 37.
The overcurrent anomaly hold circuit 37 is composed, for instance, of flip-flop circuit, and the anomaly cancellation circuit 38 is composed to cancel the anomaly hold by said flip-flop circuit, for example, by a transistor Tr provided with a protection resistor Rr disposed at the input side.
The overcurrent detection circuit 36 is composed of comparator Cp, circuit DC power source Vcc, overcurrent detection resistors R1, R2, reference voltage resistors R3, R4 or like. Here the DC power current 31 is set to, for example, a voltage of 280V and the circuit DC power source Vcc to a voltage of 5xcx9c15V and, consequently, the DC power current 31 and the circuit DC power source Vcc are separate power sources; however, when the voltage of the DC power current 31 is low and composed of a voltage similar to the circuit DC power source Vcc, the DC power current 31 and the circuit DC power source Vcc may be composed of the same one. In this case, it is necessary to compose so as not to vary the voltage of the portion corresponding to the circuit DC power source Vcc during the overcurrent.
Next, respective parts of the overcurrent detection circuit 36 are set to the following operation conditions. In the following expressions, Vcc represents the voltage of the circuit DC power source Vcc, and the voltage Em1 of the positive terminal, namely, + terminal of the comparator Cp is as represented by the following expression (1).
Em1=Vccxc2x7R4/(R3+R4)xe2x80x83xe2x80x83(1)
As for the current Is flowing in the current detection resistor Rs, suppose the direction flowing from the negative pole circuit side of the inverter 32 to the negative pole of the DC current 1, shown by the arrow, be positive direction, and respective resistor values be R1 greater than  greater than Rs, R2 greater than  greater than Rs, the voltage Em2 of the negative terminal, namely, xe2x88x92 terminal of the comparator Cp is as represented by the following expression (2).                                                                         Em3                =                                  xe2x80x83                                ⁢                                                      (                                                                  -                        Is                                            ·                      Rs                                        )                                    +                                                            [                                              Vcc                        +                                                  Is                          ·                          Rs                                                                    )                                        ⁢                                          R2                      /                                              (                                                  R1                          +                          R2                                                )                                                                                                        ]                                                                          =                              xe2x80x83                            ⁢                                                (                                                            R2                      ·                      Vcc                                        -                                          R1                      ·                      Rs                      ·                      Is                                                        )                                /                                  (                                      R1                    +                    R1                                    )                                                                                        (        2        )            
Consequently, it is composed so that, if Em1 less than Em2, the output of the comparator Cp, namely, the overcurrent detection signal 36A becomes low level Low and if Em1 greater than Em2, the output of the comparator Cp, namely, the overcurrent detection signal 36A becomes high level High; therefore, an overcurrent detection signal 36 of the waveform as shown by [Comparator output voltage] of FIG. 39.
Respective section operation waveform of FIG. 39 is an operation example of the case where the inverter 32 and the motor 33 are composed of a three-phased DC brushless motor, and in this composition, respective transistors TUxcx9cTZ of the inverter 32 performs the three-phased driving for conduction of respective stator coils 33U, 33V, 33W of the motor 33 by a phase of 120 degrees, and [Conduction phase] [Transistor driving waveform] of FIG. 39 is an operation example in a state wherein U phase transistor TU conducts in ON state and Y phase transistor TY is performing a conduction of a fine pulse state by executing ON/OFF by chopping.
In this operation state, respective current state of respective transistors TUxcx9cTZ is as shown by the bold arrow line in FIG. 40xcx9cFIG. 42, and when both U phase transistor TU and Y phase transistor TY are ON state, said positive direction current flows in the overcurrent detection resistor Rs as shown in FIG. 40, and when U phase transistor TU is ON and Y phase transistor TY is OFF, as shown in FIG. 41, the current flows so as to pass through a feedback diode DV connected in parallel with V phase transistor TV, and therefore, current does not flow in the overcurrent detection resistor Rs.
Here, even when the conduction of all transistors TUxcx9cTZ is stopped, energy accumulated in the stator coils 33U, 33V of the motor 33 flows in the opposite direction, and becomes regeneration current Ir and, as shown in FIG. 42, current flows passing through the diode DV and a feed back diode DX connected in parallel with X phase transistor TX and, consequently, a negative current flowing in the direction opposed to said positive direction flows in the overcurrent detection resistor Rs.
In case of conduction state according to the [Transistor driving waveform] of FIG. 39, in the normal state
Em1 less than Em2
Overcurrent detection signal 36A=Low
consequently, the anomaly hold circuit 37 delivers a signal of the xe2x80x9cnormalxe2x80x9d side level, namely, of the low level side in the [anomaly hold circuit] in FIG. 39 to the microcomputer 35, and the microcomputer 35 delivers a control signal to drive all transistors TUxcx9cTZ to the drive circuit 43, all transistors TUxcx9cTZ operate to supply the motor 33 with three-phased AC current.
When the position detection signal of the rotor 33R is not obtained for some reason, the current value delivered from the DC power source 31 to the inverter 32 becomes, for instance, a predetermined value preventing overcurrent damage of transistors TUxcx9cTZ by the overcurrent and magnetic decrease of the magnetized pole of the rotor 33R, and as [Rs current and overcurrent protection level] of FIG. 39, for instance, if a current attaining xe2x80x9covercurrent protection operation level Is1xe2x80x9d flows in the overcurrent detection resistor Rs, the resistor R2 side voltage of the overcurrent detection resistor Rs lowers to a predetermined value, and the comparator CP comparison state becomes the state of [Comparator positive negative terminal input voltage (overwrite)][Comparator output voltage] of FIG. 39, and
Em1 greater than Em2
Overcurrent detection signal 36A=High
consequently, the anomaly hold circuit 37 delivers a signal of the xe2x80x9cabnormalxe2x80x9d in FIG. 39 to the microcomputer 35, and the microcomputer 35 delivers a control signal to stop all transistors TUxcx9cTZ to the drive circuit 43, all transistors TUxcx9cTZ operate, and each transistor TUxcx9cTZ itself comes in a state not to supply the motor 33 with current.
Then, as the current flowing in the motor 33 transfers to the current value Isn side as [Rs current and overcurrent protection level] of FIG. 39, the current passing through the overcurrent detection resistor Rs becomes lower than the xe2x80x9covercurrent protection operation level Is1xe2x80x9d and the overcurrent detection signal 36A of the comparator CP returns to the Low side as [Comparator output voltage] of FIG. 39, but the overcurrent anomaly hold circuit 37 keeps on holding xe2x80x9cabnormalxe2x80x9d state, as [abnormality hold circuit] in FIG. 39, and this hold is cancelled by the cancel operation of the anomaly cancellation circuit 38 by the control from the microcomputer 35 and returns to xe2x80x9cnormalxe2x80x9d side.
Here, in [Rs current and overcurrent protection level] of FIG. 39, the portion where the xe2x80x9cregeneration current periodxe2x80x9d after the inverter 33 stop flows toward xe2x80x9cxe2x88x92Axe2x80x9d side, is a portion of regenerated current Ir where stator coil respective transistor TUxcx9cTZ itself of the inverter 33 doesn""t supply the motor 33 with current, as mentioned above, but that is generated by the energy accumulated in the stator coil 33U, 33V of he motor 33. In other words, in this rotation state, the motor 33 results in operating the power generation similarly to a generator, and the current by this power generation operation appears as regenerated current Ir.
In such a prior art, as it is necessary to provide, besides overcurrent detection circuit, an overcurrent anomaly hold circuit, and an overcurrent anomaly cancel circuit, apparatus whose composition becomes complicated can not be supplied easily and at a low price, and in addition, anomaly or faults also happen in these overcurrent anomaly hold circuit or overcurrent anomaly cancel circuit, making the maintenance more difficult disadvantageously.
The present invention has an object to resolve problems of such prior art, namely, necessity to provide a switching device to form an imaginary neutral point and a composition for driving control of the same, impossibility to shorten the time to the synchronous operation by a stationary position detection and necessity of a considerably long time, impossibility to transit to the cyclic operation by a stationary position detection, increase of vibration and noise of the motor itself and compressor according to the modification and adjustment of output voltage, impossibility to supply easily and at a low price an apparatus whose composition becomes complicated, and moreover, difficulty of maintenance due to anomaly or faults that happen in these overcurrent anomaly hold circuit or overcurrent anomaly cancel circuit.
Therefore, as means to solve such problems,
in a motor apparatus such as DC brushless motor comprising a rotor having a plurality of magnetized poles, and a multiple-phase stator coil disposed to supply said rotor with rotational field during the conduction, wherein a rotational field is formed by conducting a predetermined said stator coil with voltage generated in an inverter circuit, and the time to perform said conduction is controlled based on a position detection signal obtained by comparing and detecting the induced voltage generated in said stator coil of the phase not conducted as above by the rotation of said rotor and a predetermined voltage by means of a comparator provided for each phase of said multiple phases,
a first composition comprising
a comparison input means for inputting a first divided voltage dividing the voltage of said respective phase stator coil to the positive terminal of the comparator for said respective phase, and inputting a second divided voltage obtained by dividing the voltage between said first divided voltage of the phase different from the phase inputting to said positive phase and the imaginary neutral point voltage obtained by dividing the bus voltage of said inverter circuit to the negative terminal of said comparator, and
a position detection means for obtaining said position detection signal by detecting the intersection of the voltage portion based on said induced voltage in said first divided voltage and said second divided voltage by said respective comparator,
a second composition, wherein
in said first composition,
said position detection signal is obtained at the time position shifted from the intersection of said induction voltage and said imaginary neutral point voltage, by making the phase of said stator coil for obtaining said second divided voltage a phase following the phase of said stator coil obtaining said first divided voltage,
a third composition, wherein
in said first composition,
said position detection signal is obtained at the time position shifted from the intersection of said induction voltage and said imaginary neutral point voltage, by making the phase of said stator coil for obtaining said second divided voltage a phase preceding the phase of said stator coil obtaining said first divided voltage,
a fourth composition, wherein
in said first compositionxcx9cthird composition,
a condenser for absorbing noise component of the voltage input to said respective comparator and attenuating the waveform is provided,
a fifth composition, including
in a motor apparatus such as DC brushless motor comprising a rotor having a plurality of magnetized poles, and a multiple-phase stator coil disposed to supply said rotor with rotational field during the conduction, wherein a rotational field is formed by conducting a predetermined said stator coil with voltage generated in an inverter circuit, and the time to perform said conduction is controlled based on a position detection signal obtained by comparing and detecting the induced voltage generated in said stator coil of the phase not conducted as above by the rotation of said rotor and a predetermined voltage by means of a comparator provided for each phase of said multiple phases,
a masking time control means for controlling the increase/decrease of position detection masking time for regulating the detection of said position detection signal following a preceding conversion time point, at the start-up of said inverter circuit 12, in response to the number of times of said position detection signal obtained after the beginning of said start-up,
a sixth composition, including
in addition to this fifth composition,
a conversion time control means for controlling the increase/decrease of conversion delay time for regulating the conversion time point following said preceding position detection signal at said start-up, in response to the number of times of said position detection signal obtained after the beginning of said start-up,
a seventh composition, including
in addition to this fifth composition,
a driving frequency increase/decrease control means for controlling the increase rate of said inverter circuit driving frequency immediately after the beginning of said start-up, by an increase rate higher than said driving frequency increase rate during the stationary operation of said inverter circuit,
an eighth composition, wherein
in said fifth composition,
said control to increase/decrease the position detection masking time is performed only from the time point of the beginning of said start-up to the time point when the revolution of said rotor attains a predetermined number of revolution,
a first {ninth} composition, wherein
in said sixth composition,
said control to increase/decrease the conversion delay time is performed only from the time point of the beginning of said start-up to the time point when the revolution of said rotor attains a predetermined number of revolution,
a tenth composition, wherein
in said seventh composition,
said control by the higher increase rate is performed only from the time point of the beginning of said start-up to the time point when the revolution of said rotor attains a predetermined number of revolution,
an eleventh composition, comprising
in a motor apparatus such as DC brushless motor similar to the motor apparatus in said fifth composition,
a masking time control means for controlling the increase/decrease of position detection masking time for regulating the detection of said position detection signal following a preceding conversion time point, at the start-up of said inverter circuit 12, in response to the number of times of said position detection signal obtained after the beginning of said start-up,
a conversion time control means for controlling the increase/decrease of conversion delay time for regulating the conversion time point following said preceding position detection signal at said start-up, in response to the number of times of said position detection signal obtained after the beginning of said start-up, and
a driving frequency increase/decrease control means for controlling the increase rate of said inverter circuit driving frequency immediately after the beginning of said start-up, by an increase rate higher than said driving frequency increase rate during the stationary operation of said inverter circuit,
a twelfth composition, comprising
in a motor apparatus such as DC brushless motor comprising a rotor having a plurality of magnetized poles, and a multiple-phase stator coil disposed to supply said rotor with rotational field during the conduction, wherein a rotational field is formed by conducting a predetermined said stator coil with voltage generated in an inverter circuit, and the time to perform said conduction is controlled based on a position detection signal obtained by comparing and detecting the induced voltage generated in said stator coil of the phase not conducted as above by the rotation of said rotor and a predetermined voltage by means of a comparator provided for each phase of said multiple phases,
a load state distinction means for distinguishing as stable state where the load driven be said rotor is table, when the variation of number of revolution of said rotor obtained based on said position detection signal is within a predetermined range for a predetermined time, and
a control hold means for holding the control state of said pulse amplitude modification voltage at the control state at the time of said distinction when it is distinguished as said stable state,
a thirteenth composition, comprising
in place of said control hold means of said twelfth composition,
a control cycle modification means for changing said pulse amplitude modification voltage control cycle to a control cycle longer that the control cycle at the time of said distinction,
a fourteenth composition, comprising
in an inverter driving electric motor apparatus for driving an electric motor by an inverter converting DC power source into AC power source, and holding/canceling the overcurrent protection operation for stopping said inverter driving based on the output of overcurrent detection, by comparing the detection voltage obtained by sensing the current supplied to said inverter from said DC power source and a predetermined reference voltage by means of a comparator,
a hold/cancellation means for performing said hold, or said hold and cancellation, based on the hysteresis operation of said comparator,
a fifteenth composition, wherein
in said fourteenth composition,
said cancellation is performed based on reset operation of said hystxc3xa9rxc3xa9sis operation when the regenerated current of said electric motor after said stop has done becomes a predetermined negative current, and
a sixteenth composition, wherein
in said fourteenth composition,
said cancellation is performed based on the control of a microcomputer controlling said inverter driving, without reset operation of said hystxc3xa9rxc3xa9sis operation, are proposed.